Infectious diseases of the hoof, such as hairy hoof warts (papillomatous digital dermatitis, or PDD), hoof rot (interdigital phlegmon), and stable hoof rot (interdigital dermatitis), are common in farm animals such as sheep, goats, horses, dairy cows, and beef cattle. Hoof warts were first reported in Italy in 1974, and since that time, have spread throughout the world. Since the late 1980's, hoof warts have been a significant source of bovine lameness, and have had a large negative economic impact on the dairy industry. For example, a recent study by the U.S. Department of Agriculture concluded that 47% of all dairy herds in the United States are affected by PDD, with 78% of those herds reporting their first cases in 1993 or later.
Clinically, PDD appears as a lameness outbreak within an animal herd. It is a superficial skin disease of the animal digit with variable presentation, depending on the stage of the lesion, from painful, moist, strawberry-like lesions to raised, hairy, wart-like lesions. It can result in severe lameness, and even death, if not properly treated. For dairy cows, hoof warts are also associated with losses in milk production, reproductive efficiency, and body weight.
Although PDD was originally believed to be caused by a virus, it is now believed that PDD is caused by one or more bacteria. Researchers have isolated two different spirochete species of bacteria from numerous PDD lesions, but have been unable to replicate the infectious disease in healthy animals using purified cultures of these organisms, signifying that additional causative agents and/or environmental conditions are necessary to bring about the disease.
Hoof rot, or interdigital phlegmon, is an infection of the soft tissue between the claws of the feet. In equine animals, it is also known as hoof thrush. Here, the term “hoof rot” will be used to indicate both hoof rot and hoof thrush. Hoof rot is caused by the anaerobic bacterium, Fusobacterium necrophorum. The anaerobes Dichelobacter (Bacteriodes) nodosus and Prevotella melaninogenicus have also been implicated. The bacteria invade the skin of the foot at injured or damaged skin areas, and initially cause a painful swelling of the skin between the claws. A fissure or crack then develops along the swollen area for part or all of the length of the interdigital space. If left untreated, hoof rot can enter the joints, bones, and/or tendons of the foot, making recovery from the infection unlikely. Animals with hoof rot can have a mild fever, loss of appetite and accompanying weight loss, and develop mild to severe lameness.
Interdigital dermatitis, or stable hoof rot, is generally a chronic inflammation of the skin in the area between the toes of the feet (interdigital cleft). This infection is caused by the bacterium Dichelobacter nodosus. The skin in the area of the interdigital cleft will appear puffy with a dry exudation which will cause a crust to form. The condition may occasionally cause lameness or heel crack/heel erosion but generally results in an alteration in the animal's gait.
At present, hoof warts, hoof rot and stable hoof rot are treated in several ways. The most effective treatment is the use of antibiotics, such as tetracycline, lincomycin, spectinomycin, penicillin, oxytetracycline, and ampicillin. These are topically applied to the affected area via use of footbaths, sprays, or footwraps for hoof warts and systemically for hoof rot. While antibiotics are effective in treating these infectious diseases, there are several drawbacks associated with antibiotic use. Antibiotics are expensive, and there is concern, especially with dairy cows, that the use of antibiotics may result in the presence of antibiotic residues in the animal or its milk. Further, extended use of antibiotics may result in the development of an antibiotic-resistant bacteria strain. It would be advantageous to use fewer dosages or lower dosages of antibiotics to effectively treat hoof rot.
The use of chemical-based germicides has also been tried as a treatment to prevent and/or control hoof rot, hoof warts, and stable hoof rot. Although some germicides, such as those containing copper sulfate and zinc sulfate, have some efficacy against hoof rot and stable hoof rot, they are ineffective against hoof warts. Quaternary ammonium compounds have also been used, but have never been proven to be effective against PDD. Such compounds are in addition ineffective at high dilutions, such as those used in foot baths, and many are expensive. Likewise, combinations of hydrogen peroxide and peracetic acid have been used, but also are not effective against PDD, and suffer from stability and storage problems. This chemical combination is also irritating to the hoof at the recommended treatment concentrations.
There have been anecdotal reports of success with formaldehyde against PDD, but controlled trials indicate that formaldehyde is less effective than antibiotics. Additionally, formaldehyde is classified as a carcinogen and toxin, and it is illegal to use it in some parts of the United States. Further, use of too high a concentration of formaldehyde can result in destruction of healthy hoof tissue, or can even lead to sloughing of the hoof. Thus, the use of formaldehyde is neither feasible nor effective in treating foot rot, stable foot rot, and PDD.
As stated above, footbaths comprising a germicide, such as copper sulfate or hydrogen peroxide, or even an antibiotic, are commonly used to prevent hoof rot, stable hoof rot, and/or PDD. Foot baths are typically dilutions of spray or footwrap compositions. However, foot baths are often ineffective, because the medicament washes off easily, or is tracked off as the animal walks away from the bath. Further, there is typically little wound protection provided by the treatment using a foot bath.
U.S. Pat. No. 5,780,064 discloses the use of an aqueous germicidal composition comprising a copper salt, a quaternary ammonium compound, and a peroxide, to treat and prevent PDD. This patent fails to disclose the presently claimed invention.
There is a need for a composition that is effective in preventing and treating foot rot, stable foot rot, and PDD, that is affordable. This composition must also minimize the use of antibiotics. There is a further need for a composition that can be used in a footbath effectively. Further, there is a need for germicidal compositions that are effective in prevent dental caries and gum disease.